在一个关系型数据库中， 参照完整性约束可以通过( ) 来实现。
- A.主码
- B.候选码
- C.外码
- D.锁
正确答案及解析
正确答案
解析
参照完整性/引用完整性：规定，若F是基本关系R的外码，它与基本关系S的主码K，相对应（基本关系R和S不一定是不同的关系），则R中每个元组在F上的值必须为：或者取空值；或者等于S中某个元组的主码值。
所以，在一个关系型数据库中，参照完整性约束可以通过外码来实现。
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